1. Field of the Invention
This invention generally relates to ligating instruments and more particularly to instruments for dispensing a plurality of ligating bands to one or more internal sites within a patient's body in a single ligation procedure, without removing the instrument between successive ligating band placements.
2. Brief Description of Related Art
The treatment of various types of lesions including internal hemorrhoids and varices by ligation within the alimentary canal in order to stop bleeding is well known. The object of ligation is to position an elastic cord, or ligating band, at the lesion to stop circulation through tissue and allow the tissue to necrose whereupon the body sloughs off the necrotic or dead tissue.
Surgical ligation has also been employed in female and male sterilization procedures. In the case of tubal ligation in female patients, ligating rings or bands are placed on a folded-over loop portion of each Fallopian tube, blocking the path from uterus to ovaries, and thereby preventing fertilization of an ovum. In the case of male sterilization, a ligating band may similarly be placed on a folded-over loop portion of the vas deferens, thus preventing passage of spermatozoa from the testes.
The following United States Letters Patent disclose various embodiments of ligating instruments that are useful for dispensing a ligating band at a designated site within a patient: 3,760,810 to Van Hoorn; 4,257,419 to Goltner, et al.; and 4,735,194 to Stiegmann. Each of the foregoing instruments dispenses a single ligating band or a single set of ligating bands at a single location. None suggests dispensing ligating bands at discrete locations. The Van Hoorn patent does disclose the possibility of depositing plural ligating bands; however, Van Hoorn seems only to suggest dispensing plural ligating bands at a single site in a single operation. The apparatus disclosed in the Van Hoorn, Goltner or Stiegmann patents apparently would have to rely on an operator's sense of touch in order to displace the inner tube by an incremental distance corresponding to the thickness of a stretched ligating band to deposit a plurality of bands at different sites. That would be very difficult to accomplish. Thus, when it is desired to deposit ligating bands at different sites, the common practice has been to withdraw the entire instrument from the patient and load a new ligating band onto the inner tube. Loading ligating bands on an instrument requires special tools and could be time consuming particularly if the special tooling must be retrieved to install each ligating band individually while the instrument is withdrawn. Each of these instruments requires some structure, such as special stoppers or overtubes, for preventing the premature dispensing of the ligating band. Consequently, none of these instruments was readily adapted for dispensing ligating bands at different sites without withdrawing the instrument after each individual site is ligated.
Aimed at solving the aforementioned problems, the following United States Letters Patent disclose various embodiments of ligating instruments which are designed to deposit or place a plurality of ligating bands at one or more internal sites within a patient without the necessity of withdrawing the ligating instrument to reload successive ligating bands: 3,985,138 to Jarvik; 4,226,239 to Polk et al.; 3,870,048 to Yoon; 5,207,690 to Rohrabacher et al.; and 5,269,789 to Chin.
U.S. Pat. No. 3,985,138 to Jarvik discloses a ligature gun for placing a plurality of preformed suture loops which are tightened around bleeders after emplacement. The successive preformed suture loops are advanced to the dispensing end of the ligature gun by rotation of a threaded rod onto which the loops have been preloaded. The Jarvik ligature gun comprises large number of mechanical parts and is relatively complex in design and operation.
U.S. Pat. No. 3,870,048 to Yoon discloses the use of elastic bands or rings in tubal ligation. The Yoon device is constructed so as to permit two or more ligating rings to be loaded at the same time, but discharged separately at different times and in succession to one another, even at different locations, all without removing the ligating device from the patient's body cavity. Yoon's device is also relatively complex.
U.S. Pat. No. 4,226,239 to Polk et al. also describes a surgical ligating instrument for tubal ligation within a human or animal body, by the application of two or more elastic ligating rings without the necessity of removing the instrument from the patient for each ligating ring. In the device of Polk et al., a number of ligating rings are stretched over a cylindrical shaft which is slidably and concentrically received within an outer cylindrical sleeve. As the cylindrical shaft is withdrawn proximally with respect to the outer sleeve, the outer sleeve successively forces the ligating rings off of the shaft, preferably one at time. The extent of relative motion between the shaft and the sleeve is controlled by a mechanical stop at the proximal end of the shaft, located in the pistol handle of the instrument. The operator can be sure that a only single band has been placed only if the mechanical stop is precisely calibrated to the width of an individual ligating ring. The ligator disclosed by Polk et al. requires the molding of several separate components of a manufacturing tolerance sufficiently precise to not permit the elastic band to be pinched or caught between the sleeve and shaft. U.S. Pat. No. 4,860,746 discloses a device similar to that of Polk et al., and similarly requires precise manufacturing tolerances.
U.S. Pat. No. 5,207,690 to Rohrabacher et al. teaches that successive ligating rings may be slipped off of the cylindrical shaft onto which they have been preloaded by the use of separate forceps.
U.S. Pat. No. 5,269,789 to Chin et al. discloses a ligating band dispenser located at the distal end of an elongated introducer, which dispenser responds to manipulation of an operating structure at the proximal end of the introducer. The dispenser comprises first and second coaxially located, interfitted segments that support ligating bands at a plurality of axially spaced positions thereon. Each segment includes a spaced ligating band engagement structure for engaging portions of each ligating band or set of bands. One of the segments connects to the operating structure for being moved between first and second positions relative to the other of the segments. This motion dispenses one of the ligating bands from the distal end of the ligating instrument and moves the remaining ligating bands distally with respect to the dispensing means thereby to position a successive ligating band for being dispensed at a different site, as in some of the aforementioned devices as well. The Chin et al. instrument, however, is an improvement over those devices in that it is specially constructed to prevent more than a single ligating band from being dispensed in response to a single actuation of the operating structure. On the other hand, the ligating bands are initially greatly stretched when loaded onto the Chin et al. instrument, bringing about the necessity of a relatively strong spring in order to slide the bands distally. The operator's hand must work against this spring when actuating the device. Moreover, advancement of the ligating bands toward the dispensing end of the device requires the bands to be stretched even further than their initial stretched conditions. Such stretching requires even greater force to applied by the operator's hand. U.S. Pat. No. 5,356,416 to Chu et al. discloses a device similar to Chin et al. further including a sclerotherapy needle for administering a sclerotherapy agent as an alternative to ligating a lesion.
U.S. Pat. No. 5,398,844 describes a multiple band ligator which is currently being introduced to market. The Wilson Cook "Six-shooter," product no. MLV-6, which is based on an invention by Mr. Munir Ahmed of DabeGran Technologies, is also a multiple band ligator which is being introduced to the market. These devices overcome the limitations of single band ligation because they can deploy multiple bands (6 and 5 bands respectively) without removal of the scope from the patient. Neither design requires the use of an overtube which further reduces the risks of esophageal tears and perforations associated with endoscopic procedures. However, these products utilize draw strings which are tensioned upon application of a pulling force via a trigger. These draw strings or tensioners are contained within a conduit which runs the length of the working channel of the endoscope. The space occupied by the conduit inhibits the suction irrigation that occurs within the working channel. The blood in the working channel inhibits the field of view and thereby tends to lengthen the time of the procedure and increase the difficulty to the operator. The device according to the '844 patent, for example, is believed to decrease a 2.8 mm working channel by 42%. Further, each of these devices requires intricate manual assembly of the bands, the individual trip lines, and the external actuating mechanism for releasing the bands.